Wheel bearing units both for driven and non-driven wheels are known since long and are nowadays used on a plurality of car types. An example of such a unit is shown in the U.S. Pat. No. 3,757,883.
These wheel bearing units can be made in different dimensions. They all have the property of taking up torque load, they have low weight and are easily mounted. The type of wheel bearing units, which is intended for driven frontwheels, usually has a splined central bore for attachment to the journal of the driving joint or it is made integral with such a driving joint.
Most rear-wheel driven cars have a so-called rigid rear shaft. Such a structure incorporates a rigid casing, in which the two drive shafts are supported. Every shaft has an interior support in the differential gearing and an outer bearing at the wheel. This bearing is situated a short distance from the end of the shaft for giving space to the brake mechanism. Characterizing for this structure is that the shaft, beside torsional forces from the drive, will have to absorb also bending forces from the torque loads acting from the road upon the wheel, and it must be dimensioned in relation thereto. With disc brakes at the rear, and the angular accuracy then required, also small deflections of the shaft cause problems.
In FIG. 1 is shown such a known structure, where a rigid rear shaft is supported at its outer end. The very drive shaft is designated 1. This shaft, which has a robust design, is enclosed by a casing 2 and is via a taper bearing 3 supported in this casing, which in turn is suspended in the car. The shaft 1 at one of its ends is provided with a flange 4, to which the rear wheel (not shown) intended to be attached by means of bolts. 5. A brake disc 6 is also attached to this flange 4. This brake disc 6 also incorporates a cylindrical part 7 intended to operate as a brake drum. The disc-shaped part 6 extends through the brake housing 8, and the disc 6 together with the brake housing 8 constitute the main brake.
The drum-shaped part 7 of the brake disc is intended for the parking brake 9, which is actuated by a pull wire 10 or the like.
By using a moment supporting wheel bearing unit, e.g. of the type defined in the abovementioned U.S. Pat. No. 3,757,883, the bending moment is removed from the shaft. This is then dimensioned for rotation only. There will neither be any problem with the brake disc becoming skewed.
Hitherto known bearing units have not been possible to use for driven rear wheels due to the space required by the drum brake equipment. This applies both to drum brake as a main brake and disc brake with drums for the parking brake.